Guice: Inject class with constructor with own parameters?

Question

I have a problem with Guice. I would like to show this with an example. I want to pass the parameters of this constructor always dynamically, so e.g. new Test("bob", 765);. I also want some fields (like here SomeOtherObject) to be injected by Guice. How can I do this? Thanks in advance!

public class Test {

private String name;
private int id;

//Needs to be injected by Guice
@Inject
SomeOtherObject object;

public Test(String name, int id) {
    this.name = name;
    this.id = id;
}

}

Answer 1

Guice's AssistedInject feature is a good way to handle this.

Basically you define a factory to get Test objects with:

public interface TestFactory {
    public Test create(String name, int id);
}

Augment the Test class's @Inject constructor with @Assisted annotation:

public class Test {
    @Inject
    public Test(SomeOtherObject object, @Assisted String name, @Assisted int id) {
        this.object = object;
        this.name = name;
        this.id = id;
    }
}

And then use FactoryModuleBuilder in your Module's configure:

install(new FactoryModuleBuilder().build(TestFactory.class));

And instead of constructing Tests directly, inject a TestFactory and use it to create Tests:

public class OtherThing {
    @Inject
    TestFactory factory;

    public Test doStuff(Stirng name, int id) {
        return factory.create(name, id);
    }
}

Note: looking at the docs now, it appears that AutoFactory has been introduced as the preferred way to do this, and may be simpler.